A straightforward synthesis of glyco-2,7- and 2,8-dienes

In this paper, we report the efficient preparation of carbohydrate-derived 2,7- and 2,8-dienes. By our synthetic approach, we have quickly converted d-glucose 1 to (E)-ethyl-2,3-dideoxy-d-gluco-oct-2-enoate 5, which led to the desired (E)-ethyl-9,9-dibromo-2,3,8,9-tetradeoxy-4,5,6,7-tetra-O-trimethylsilyl-d-gluco-nona-2,8-dienoate 19 with satisfying yield.     

Cyclization of esters of 1-bromo-2-propanol and 2-bromo-1-propanol by the action of silver trifluoromethanesulfonate

Conclusions The possibility of forming 1,3-dioxalanium cations from various esters of 1-bromo-2- propanol and 2-bromo-1-propanol under conditions for the previously studied isomerization of (I) and (II) was demonstrated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 723–724, March, 1989.     

Cyclization of 1,6-enynes with allylic chromate species

[reaction: see text] Treatment of 1,6-enynes with tetramethallylchromate induces a cyclization reaction with concurrent introduction of a methallyl group. A catalytic amount of CrCl(3) combined with methallylmagnesium chloride also achieves this cyclization process. The resultant cyclic organometallic species undergo further functionalization upon reaction with electrophiles.     

Ferrier-type alkynylation reaction mediated by indium

An efficient Ferrier-type alkynylation reaction between glycals and iodoalkynes using Barbier conditions is described. These conditions require In0, InI, or InII and lead to alpha-2,3-unsaturated-C-glycosides with good stereoselectivity. When glycosyliodoalkynes are used, trehalose-derived compounds and alpha-(1-->6)-C-disaccharides are obtained.     

Palladium-catalyzed cascade cyclization-coupling reactions of 2-bromo-1,6-enynes with organoboronic acids

2-Bromo-1,6-enynes 5 with a palladium catalyst would form the alkenylpalladium intermediates via an intramolecular Heck reaction, which were cross-coupled with various organoboronic acids 8 to give the cyclization-coupling products 6 in synthetically valuable yields.     

Cyclization of 6-bromo-1,2-epoxyhexane promoted by metal-halogen exchange: unexpected regioselectivity

Treatment of 6-bromo-1,2-epoxyhexane (1) with one quivalent of $\text{sec}$-butyllithium afforded a 95:5 mixture of cyclopentylmethanol (4): cyclohexanol in approximately 40% yield. An analogous tandem metal-halogen exchange/cycloalkylation process using the oxirane derivative (2) of 6-iodo-1-hexene gave virtually the same mixture of alcohols in >60% yield.     

Cyclization of 1-(pentafluorophenyl)-2- aminoalkanols

The nitro group in 1-(pentafluorophenyl)-2-nitroalkanols is reduced selectively to a hydroxylamino or amino group by controlled potential electrochemical reduction. The pentafluoro-phenylaminoalkanols cyclize readily on heating in dimethylformamide to give homologs of 4,5,6,7-tetrafluoroindole. It is shown that the intermediate in the cyclization of 1-pentafluorophenyl-2-aminoethanol is 3-hydroxy-4,5,6,7-tetrafluoroindoline. Cyclization of 1-pentafluorophenyl-2-hydroxyaminoethanol gave 1,3 -dihydroxy-4,5,6,7-tetrafluoroindoline.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 622–625, May, 1970.     

An efficient synthesis of optically active five- and six-membered cyclic compounds with selectable stereo-controls by a Ti(II)-mediated cyclization of chiral secondary 2,7- and 2,8-enyn-1-ol derivatives

Ti(II)-mediated cyclization of readily accessible optically active secondary 2,7- and 2,8-enyn-1-ol derivatives enables the selective preparation of any one of the four possible stereoisomers of the cyclized product with high optical purity.     

Synthesis of 4,5-dihydro-2-diethylamino-4-thioxo-4-phenoxy-5-chloro-1,3,4-thiazaphosphole and 3,7-bis(diisopropylamino)-1-thioxobicyclo[3.3.0]-4,6-dithia-2,8-diaza-1-phosphaocta-2,7-diene

The product of the reaction of 0-phenylisothiocyanatodichloromethylthiophosphonate with diethylamine in the presence of Et₃N is 4,5-dihydro-2-diethyl-amino-4-thioxo-4-phenoxy-5-chloro-1,3,4-thiazaphosphole. 3,7-Bis(diisopropyl-amino)-1-thioxobicyclo-[3.3.0]-4,6-dithia-2,8-diaza-1-phosphaocta-2,7-diene was obtained as the result of the reaction of diisothiocyanatodichloromethylthiophosphonate with diisopropylamine and triethylamine. IR, PMR, and³¹P NMR spectroscopy was used to demonstrate the structures of the products synthesized.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Science Center, Russian Academy of Sciences, 420083 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 462–463, February, 1992.     

Syntheses of 1-(2-bromo-3-hydroxypropyl)-and 1-(2-bromo-2-propenyl)isatins and theirβ-thiosemicarbazones

Only the bromine atom at the primary carbon atom participates in nucleophilic replacement by a trifluoroacetate ion and elimination of HBr in 1-(2,3-dibromopropyl)isatin.Institute for the Biological Protection of Vegetation, Academy of Sciences of the Republic of Moldova, 2060 Kishinev, Moldova. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 308–310, March, 1998.     

Preparation of hexafluoro-1,8- and -2,7-naphthyridine

Hexachloro-1,8- and -2,7-naphthyridine have been prepared from 2,7-dichloro-1,8-naphthyridine and 1,3,6,8-tetrachloro-2,7- naphthyridine respectively. From these products and their starting materials a series of partially and totally fluorine substituted compounds have been derived.     

Synthesis of 2,7-Diazabicyclo[3.3.0]octane and 2,7-Diazabicyclo[3.3.0]oct-4-ene Derivatives via Cyclization Reaction and Julia Reaction

2,7-Diazabicyclo[3.3.0]octan-4-ol (1) and 2,7-diazabicyclo[3.3.0]oct-4-ene (2) are synthesized by the desulfonylation using Mg-HgCl₂(cat.) of β-hydroxy sulfone derivatives which have been prepared via cyclization of sulfone ester derivative.     

X-ray structural and spectral study of 1:2 solvate of 2,7-dinitro-4-bromo-10,10-dihydroxyphenanthren-9-one with dimethylformamide

An x-ray structural study showed the total similarity of the behavior of 2,4,7-trinitro- and 2,7-dinitro-4-bromo-9,10-phenanthrenequinones dissolved in aqueous DMF: addition of a molecule of water at one of the two carbonyl groups with formation of the corresponding 10,10-dihydroxyphenanthren-9-ones takes place in both cases in soft conditions. These products of hydration exist as hydrogen-bonded solvates with molecules of the solvent whose crystals are isostructural to each other. The results of the x-ray structural study are in agreement with the data from the IR absorption and electron absorption spectra; their comparison suggests the existence of equilibrium between the starting compounds and the products of hydration, and the equilibrium position is a function of the polarity of the basic solvent.A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, Moscow 117813. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 910–916, April, 1992.     

An Efficient Synthesis of 2,8-Diazabicyclo[4.3.0]-nonane Derivatives via Intramolecular Cyclization Reaction

Novel 5-functionalized-2,8-diazabicyclo[4.3.0]nonane derivatives 5 were synthesized from epoxide 1 through 4 steps in 46.7～52.6% yield.     

Regio- and diastereoselective reduction of nonenolizable alpha-diketones to acyloins mediated by indium metal

[reaction: see text] Alpha-diketones are efficiently reduced with indium metal in methanol-water in the presence of NH(4)Cl, LiCl, or NaCl to give regio- and diastereoselectively the corresponding acyloins in good to excellent yield. The cleavage of the acyloins under Pb(OAc)(4)/MeOH-PhH condition provides a convenient and regioselective access to highly functionalized cyclopentane carboxaldehydes, potential building blocks in organic syntheses.     

Cyclization of 1-hydroxy-2-(oxoalkynyl)anthraquinones

Procedures were developed for the heterocyclization of 2-benzoylethynyl-1-hydroxy-and 1-hydroxy-2-(1-oxo-3-phenylpropynyl)anthraquinone. The regioselective preparation of 2-substituted anthra[1,2-b]pyran-4,7,12-triones was demonstrated to be possible under mild conditions.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2686–2692, December, 2004.